The present invention relates to a transmission mounted on a vehicle and, more specifically, to a shifting device for a transmission equipped with a synchronizing mechanism.
The operation for shifting a transmission equipped with a synchronizing mechanism is such that a clutch sleeve is actuated in a state where a friction clutch arranged between the transmission and the engine is disconnected, a synchronizer ring is pushed so that the rotational speed of the output shaft, i.e., of the clutch sleeve is brought into synchronism with the rotational speed of a speed change gear that is to be brought into engagement and, then, the clutch sleeve is brought into engagement with dog teeth of the speed change gear. The synchronizing mechanism in the transmission is such that in the synchronizing operation, the chamfer of the synchronizer ring is brought into engagement with the chamfer of the spline of the clutch sleeve and after the synchronism has been established, the synchronizer ring is pushed back by the thrust of the clutch sleeve and is brought into engagement with the dog teeth. That is, in shifting the transmission equipped with the synchronizing mechanism, the largest thrust is required in the synchronizing operation at the time when the gear is to be engaged, and the next largest thrust is required for bringing the chamfer of the dog teeth into engagement with the chamfer of the spline of the clutch sleeve. When the gear is to be disengaged, on the other hand, a thrust is required during from the start of the operation for disengaging the gear until the dog teeth are out of mesh with the spline of the clutch sleeve. Therefore, the shifting operation can be executed with the largest energy efficiency if the shift actuator that operates the shift lever of the transmission equipped with the synchronizing mechanism in the direction of shift can produce a thrust corresponding to the shift stroke position.
Meanwhile, as a shift actuator for actuating the shift lever for operating the clutch sleeve, there has been used a fluid pressure cylinder using a fluid pressure such as pneumatic pressure or hydraulic pressure as a source of operation. In recent years, further, there has been proposed an actuator of the type of an electric motor as a shift actuator for a transmission mounted on a vehicle which is provided with neither a source of compressed air nor a source of hydraulic pressure.
In the conventional shifting device for the transmission, the shift actuator has been operated with a constant thrust over the whole shift stroke either when the gear is to be engaged or is to be disengaged. When the thrust of the shift actuator is small, therefore, an extended period of time is required particularly for the synchronizing operation and, hence, execution of the shifting operation requires an extended period of time. When the thrust of the shift actuator is increased, on the other hand, a large shock occurs at the time of engaging the gears and, besides, energy is consumed wastefully.
It is, therefore, an object of the present invention to provide a shifting device for a transmission capable of effecting the shifting operation with the highest energy efficiency by letting the shift actuator to produce a thrust corresponding to the shift stroke position to operate the shift lever of the transmission equipped with the synchronizing mechanism in the direction of shift.
In order to accomplish the above-mentioned object according to the present invention, there is provided a shifting device for operating the shift lever of a transmission equipped with a synchronizing mechanism in the direction of shift to bring the gear into engagement or disengagement, comprising:
a shift actuator comprising an operation rod that is engaged with an operation member coupled to said shift lever, a magnetic moving member arranged on the outer peripheral surface of said operation rod, a cylindrical fixed yoke arranged surrounding said magnetic moving member, and a pair of coils arranged side by side in the axial direction inside said fixed yoke;
a shift stroke sensor for detecting the shift stroke position of said shift lever; and
a control means for controlling the electric power supplied to said pair of coils of said shift actuator based on a signal from said shift stroke sensor; wherein
said control means controls the electric power fed to said pair of coils of said shift actuator in response to the shift stroke position detected by said shift stroke sensor.
The control means, in the gear-engaging operation, sets the electric power fed to said pair of coils to the first electric power up to a position where the synchronism of said synchronizing mechanism ends, and sets the electric power to the second electric power smaller than said first electric power after the synchronism end position is passed until a position where the engagement between the chamfer of a clutch sleeve of the synchronizing mechanism and the chamfer of the dog teeth ends.
Further, the control means, in the gear-disengaging operation, sets the electric power fed to said pair of coils to the third electric power smaller than said second electric power over a range in which the clutch sleeve of said synchronizing mechanism is in mesh with the dog teeth.
According to the present invention, further, there is provided a shifting device for operating the shift lever of a transmission equipped with a synchronizing mechanism in the direction of shift, comprising:
a shift actuator comprising the first electromagnetic solenoid and the second electromagnetic solenoid for operating the operation member coupled to said shift lever in the directions opposite to each other;
a shift stroke sensor for detecting the shift stroke position of said shift lever; and
a control means for controlling the electric power fed to said first electromagnetic solenoid and to said second electromagnetic solenoid of said shift actuator based on a signal from said shift stroke sensor; wherein
said control means controls the electric power fed to said first electromagnetic solenoid and to said second electromagnetic solenoid of said shift actuator in response to the shift stroke position detected by said shift stroke sensor.
The electric power fed to said first electromagnetic solenoid and to said second electromagnetic solenoid is set based on a target thrust corresponding to the shift stroke position and on a gap between the moving iron core and the fixed iron core of the first electromagnetic solenoid and of the second electromagnetic solenoid corresponding to the shift stroke position.